Electrical plug switch



Jan. Z5 1927. 1,615,726

W. ROW

ELECTRICAL 'PLUG SWITCH Filed Nov. 2. 1925 2 Sheets-Sheet 1 4 C 2 l /0 if l w llllllnWlI--N l Patented am. 2s, 1927.

UNI-TED STATES PATENT orifice.' t

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This invention relates to improvements in electrical plug-switches` and particularly to plug switches of the used in theatres and concert halls for rapidly switching varistage lighting circuits .into use or for quickly chaljging over to diferent lighting circuits to o tain vary' stageligh.' e ccis. One object dlflgthe inventidiilgis to provide a plug switch in which the plug when inio serted into the socket is firmlyoretained or locked against accidental dislodgment and wherein the live contacts are completely enclosed and protected, thus preventing any possibility of or of damage being caused to the costumes of the performers and to stage properties.

A plug switch according to the invention comprisesa socket and a plug, the plug being adapted for insertion into the socket and 2o for rotatable movement therein. `The plug has twoI contact studs which are connected to the stage lighting circuit or other circuit to be controlled,y while the socket is formed with gaps through which said contact studs are passed when the plug is being inserted.

Fitted interiori of the socket are contacts preferably o the spring type which are normally covered by a protective ring of insulating material to prevent arcing. This ring it rotatable and it has gaps to receive the contact studs on the plug so that when said plug is rotated within` the socket to bring its contact studs into engagement with the socket contacts, said ring is simultaneously rotated to uncover said socket contacts, and

' when said plug isrrotated to disengage its contact studs from the socket contacts said ring is also rotated to cover said socket contacts.

Suitable springs may be provided for pressing the protective ring over thesocket contacts and also for quickly ejecting the plug :from the socket when switching off.

The invention is illustrated in the accompanying drawings wherein Figure 1 is a sectional view of the` 1mproved plug switch showing the `plug inserted into the socket.

Figure 2 is an elevational view partl in i section of the plug removed from the swltch.

Figure 3 is a sectional view of the socket.

Figure 4 is a plan View of Figure 3.

Figure 5 is a sectional view of the socket cover.

Figure 6 is a plan view of an insulating block forming partof the to which the spring contacts are secured.

' Figure 7 is an underside plan view of F1 lire 6.

"'gure 8 isa sectional view on line A-A 0o lof Flgure.

F igine 9 is a plan view of the protective ring for covering the socket contacts. "gute 10 is a sectional view on line B-,B

of Figure 9.

Figure 1l is a plan View of the socket' Figure 12 is a sectional view of 11. Figure 13 is a sectional view of a modified construction of plug switch included inthe mvention.

The improved plug switch illustrated in these views comprises a socket 2 and a plug 3, said plug being adapted -for insertion into the socket and for rotatable movement therein. The plug 3 is preferably formed of wood and it has two laterally proecting contact studs 4, which are opposltelly munged and are connected by wires 5 to the stage lighting circuit or other circuit to be controlled. The wires 5 pass through an axial passage 6 formed inthe plug and then through inclined passages 7, being connectedv to the contact studs 4 by terminal screws 8, see Figure 2. Y'

The socket member 2 of the plug switch comprises a casing 9 formed preferably of metal having a cover 10 which is detachably secured in position by screws, 11. Formed in the cover 10 is a hole 12 through which the plug 3 is inserted. This hole has op-A postely arranged gaps 13 through which the contact studs 4 are passed during the insertion of the plug.

Secured to the undersurface of the cover 10 is an insulatino' block 14 of square shape having a central hole 15 to receive the lug 3 and gaps 16 for the laterall contact ituds 4. Formed on the uppersurface of said insulating block are channels 17 through which. power cables (not shown) arepnssed. Apertures 18 are formed in the ends of the cover 10 in register with, ther ends. of the channels 17, so that thepower cables connected to one plug switch can be extended and connected to adjacent plug switches.

Secured to the undersurface of the insulating block 14 are two arcuately shaped contacts 19, each of which comprises two spring plates 20 and a spacing block 21 secured be- 110 .-4 with Lerares tween said plates. The contacts 19 are ar ranged directly beneath the channels 17 and the ends ci their spring plates 20 lie adjacent to the gaps 16, see Figure 'i'.

The contacts 19 are secured in position by screws 22 which pass through the block lll and are connected to the power cables in the channels 1f?. 'Arranged beneath the insulating lolocl; 14 is a protective ring 23 formed ot insulatingmaterial which is formed having a deep annular groove 2st to accommodate the contacts 19. The ring 123 is rotatable within the casing 9 and it has gaps 25 :formed in the interior wall of its groove 24C to receive the contact studs 4 when the plug is inserted into the socket.

A coil spring 26 is tted in the casing 9 and it has one end hearing against .a shoulder 27 formed on said casing and its opposite end bearing against the lower surface of the protective ring 23. This spring causes said protective ringv 23 to be firmly pressed against the insulating block 14 thus covering the live contact-s 19.

The lower end oi' the socket casing 9 is shaped to forni a cylindrical chamber 28 wherein a block 29 is slidaloly mounted. A

coiled spring 3() is fitted in said chamber and it hears against the lower end of the block 29 serving to normally maintain said block firmly pressed against the undersurface of the protective ring 23--see Figure 3.

In use, the power leads are passed through the channels 17 in the insulating Ablock 14 and are electrically connected to the spring contacts19 of the socket by the screws 22 while the wires 5 rom the stage lighting circuit or othel" circuit to be controlled are connected to the contact studs 4 oi the plu 3 by the terminal screws 8. Y

When switching-on, theplug 3 isinserted into the socket 2 through the'hole 12 so that the contact studs 4 pass through the gaps 13, and the plug is. then pressed inwardly against .the block 29 todepress said .block against the action of its coiled spring 30. As the plug 3 is inwardly pressed the contact studs 4 pass, through the gaps 16 in the insulating block 14 and engage the gaps 25 in the wall of the protective ring 23. The plug is then rotated in the direction indicated by the arrowa in Figure 4 causing the lateral contact studs 4 to rotate the protective ring 23 and'also causing said studs to pass between and engage the spring plates 20 of the contacts 19.

Electrical contact is thus made between the contact studs 4 on the plug and the contacts 19 on the socket, so that the wires 5 from the stage hting circuit are connected to the power ca. les. The degree tof. which the, plug 3 can be rotated within the socket 2 is limlted by the engagementof the studs the spacing. blocks 21 ofthe contacts 19.H f

vWhere switchingoi, the plug 3 is rotated in the direction oi the arrow o in fl, thus rotating the protective ring 23 and da engaging the contact studs i from the contacts 19 to interrupt the circuit. The ring 23 while being rotated covers the contacts 19 so that any arcing whichvinay taire place is damped and cannot escape from the switch. By this means any possibilit5,Y ci lire or ci damage being caused "to the .costumes oi the performers and to stage cidental dislodgment of the plug oy a performer is ohviated.

When plug switches of the construction shown in Figures 1 to 12 are used for stage lighting they are preferably mounted on a suitable switchboard positioned beneath the stage floor, sp that the wires 'rom the plugs will not interfere with the performers on the stage. Y

According to the modified construction illustrated in Figure 13 the socket casing 9 is designed to enable the plug switch to he recessed or fitted directly into the stage floor. In this form of the invention, an outward flange 31 is :formed horizontally on the socket cover 10 to permit the attachment of 'the plug switch to the stage door, and small slots 32 are provided on the lower surface of thel protective ring 23 to receive pins 33 fitted to the spring pressed block 29. These slots and pins prevent the protective ring 23 from being rotated until the block 29 has been depressed against its spring 30. Thus the contacts cannot be uncovered, nor can the pluo 3 be rotated until said plug has been inserted into the socket 2 to a required distance. Guide ribs 34 are formed on the wall of the chamber 28 and grooves 35 are formed inthe block 29 to accommodate said ribs and prevent said block being in such manner-that the pins 33 will not engage the slots 32.

The invention isnot limited solely to plug switches" intended for controlling. sts

'lighting-circuits, as it can be applied with equalfacility to plug switches intended for ill lllll use with; electric irons, and other electrical appliances or apparatus.

Wh'at I do claim isz- 1. A-'socket, an a in said socket to receive a plug, gaps in said socket providing v contactstted interior-ly of said socket and arrangedto be envaged by thecontact studs of the plug, an a protective insulating member within said socket androtatable by vturning movement' of the plug"to cover or uncover theA socket contacts.

2, A socket, an insulatin .block in said socket, an aperture in said lock to accommodatea plug, gaps in said block providing clearance :for the contact studs of the plug, contacts fitted to said block and arranged for engagement by the plug contact studs; and a protective insulatin member'in abutment with said insulating lock and adapted to be rotated by turning movement of the plug to` cover or uncover the socket contacts.

3. A socket according to claim 1, wherein a springressed .block is provided'in Vthc socket to ar against the end of the plug and eject same when switchingoif.

4f. A socket according to claim l, wherein each of the contacts in-.the socket consists of Vtwo s ring platesI spacedl apart by a spacing b ook.

-5. A socket according to claim'2, wherein 4 the protective insulating` .memberhas an rannular groove tol accommodate the socket contacts, and -gaps to receive the contact studs of the plug.

6. A socket according to claim 2, wherein a 'springhis provided to -maintain the protective insulating member in clamping 'abutment with the insulating block. w

7.4 A socket, an aperture in said socket lto receive the plu gags in`said socket providing clearance or t e contact studs, contacts itted'interiorly of said socket and arran of t e plug, a protectivejnsulating member normal d for engagement by the'contact studs i y covering 4the socket contacts and 'rotatable to uncover the same, a springpressed b'lock'in the socket bearing against the plug, and means for restraining said protective member .against rotation until .depressionof said spring-pressed block.

8. A socket according o claim 7, wherein ins are provided ,on lock to engage slots in the protective insulating member and preventrotaton of said 'protective member until the saidblock is de ressed.

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'y Wilmink, ow. 

